New turtle tracking technique may aid efforts to save loggerheads

The old adage “you are what you eat” is helping scientists better understand the threatened loggerhead turtle, which is the primary nester on Central Florida’s beaches.

A study published today in the journal PLOS ONE describes how scientists at the University of Central Florida used a technique that links chemical signatures of the turtles’ diets and their watery environments to their migratory routes. They found the technique just as effective as expensive satellite tracking.

Little is known about the turtles, which spend 99 percent of their time in the water and return to the Archie Carr National Wildlife Refuge’s beach to nest once every two to three years. The 13-mile-long beach is home to the second-largest population of loggerheads in the world and to about one of every four nests those turtles lay in the United States.

While other turtles’ nests are increasing along the refuge’s shores, the loggerheads’ have been declining since 2000. The technique validated by the UCF scientists could help managers preserve the turtles’ nesting grounds, migration routes and foraging grounds, all of which are critical to their survival.

“We need good information so policy makers can focus the limited conservation funds available where they can make the greatest impact,” said Simona Ceriani, the UCF graduate student who led the study. “We all want our children to see these beautiful creatures and not just read about them in a book.”

In addition to validating the tracking technique, the study found that the foraging area for the Florida turtles is much broader than previously thought. 

“Think of these turtles as Florida tourists and snowbirds,” Ceriani said. “They come and nest and then go back to lots of different places. And while we knew some went back north, we had no idea that this was a popular destination.”

Based on her tracking, some turtles head for the water off the shores of Virginia and Delaware while others go to the Bahamas and the Gulf of Mexico. Some stay off the coast of Central Florida’s beaches. Previously, scientists believed the majority of the loggerheads headed south.

While there are efforts to protect the turtle nests on the beaches, protecting their foraging grounds is equally important, biologists say. Many turtles die because they accidently get caught in fishing nets or encounter other dangers while out at sea.

The technique Ceriani validated should aid those efforts.

She took small blood samples from turtles at the refuge and completed a chemical analysis, which measured distinct markers known as stable isotopes. She also attached transmitters to the turtles so she could follow them using the more expensive but proven satellite tracking technique. The isotope approach proved to be equally useful, and it is much less expensive.

“By combining isotope research with satellite tracking technology, we are learning exciting information about loggerhead sea turtles,” said Daniel R. Evans, a research specialist at the Sea Turtle Conservancy and co-author of the research paper. “This research helps scientists and conservation managers identify key feeding areas for loggerhead turtles and helps direct policy and regulations that protect sea turtles in these specific areas.”

Ceriani said she will continue to research the migratory routes by adding more loggerheads to the study.

Ceriani earned her bachelor’s degree at the University of Milan in Italy and was a research fellow at Florida Atlantic University before joining UCF’s PhD program in conservation biology in 2007.

Others who contributed to the study include: UCF Biologist, John Weishampel, James D. Roth from the University of Manitoba in Canada and Llewellyn M. Ehrhart from the Marine Turtle Research Group at UCF.

Several grants from Florida’s Sea Turtle Grants Program funded this study. The program gets is funding from the sale of the Florida Sea Turtle License Plate.

Sea turtle monitoring at the Archie Carr National Wildlife Refuge was coordinated through the University of Central Florida Marine Turtle Research Group, with funding from Brevard County, the Florida Fish and Wildlife Conservation Commission, the United States Fish and Wildlife Service and the United States National Marine Fisheries Service.